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authorLinus Torvalds <torvalds@linux-foundation.org>2011-07-22 19:52:18 -0400
committerLinus Torvalds <torvalds@linux-foundation.org>2011-07-22 19:52:18 -0400
commit112ec469663e09ffc815761254b52f3ca787ce83 (patch)
tree18a7d2300dc10b7c2c994107681dffc927589701 /kernel
parenta99a7d1436f9375662f35ccac8f1a1e1b0302a11 (diff)
parentcbaa51524b3224813814607177a00c350ee35d12 (diff)
Merge branch 'timers-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip
* 'timers-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip: time: Fix stupid KERN_WARN compile issue rtc: Avoid accumulating time drift in suspend/resume time: Avoid accumulating time drift in suspend/resume time: Catch invalid timespec sleep values in __timekeeping_inject_sleeptime
Diffstat (limited to 'kernel')
-rw-r--r--kernel/time/timekeeping.c28
1 files changed, 28 insertions, 0 deletions
diff --git a/kernel/time/timekeeping.c b/kernel/time/timekeeping.c
index 342408cf68dd..2b021b0e8507 100644
--- a/kernel/time/timekeeping.c
+++ b/kernel/time/timekeeping.c
@@ -604,6 +604,12 @@ static struct timespec timekeeping_suspend_time;
604 */ 604 */
605static void __timekeeping_inject_sleeptime(struct timespec *delta) 605static void __timekeeping_inject_sleeptime(struct timespec *delta)
606{ 606{
607 if (!timespec_valid(delta)) {
608 printk(KERN_WARNING "__timekeeping_inject_sleeptime: Invalid "
609 "sleep delta value!\n");
610 return;
611 }
612
607 xtime = timespec_add(xtime, *delta); 613 xtime = timespec_add(xtime, *delta);
608 wall_to_monotonic = timespec_sub(wall_to_monotonic, *delta); 614 wall_to_monotonic = timespec_sub(wall_to_monotonic, *delta);
609 total_sleep_time = timespec_add(total_sleep_time, *delta); 615 total_sleep_time = timespec_add(total_sleep_time, *delta);
@@ -686,12 +692,34 @@ static void timekeeping_resume(void)
686static int timekeeping_suspend(void) 692static int timekeeping_suspend(void)
687{ 693{
688 unsigned long flags; 694 unsigned long flags;
695 struct timespec delta, delta_delta;
696 static struct timespec old_delta;
689 697
690 read_persistent_clock(&timekeeping_suspend_time); 698 read_persistent_clock(&timekeeping_suspend_time);
691 699
692 write_seqlock_irqsave(&xtime_lock, flags); 700 write_seqlock_irqsave(&xtime_lock, flags);
693 timekeeping_forward_now(); 701 timekeeping_forward_now();
694 timekeeping_suspended = 1; 702 timekeeping_suspended = 1;
703
704 /*
705 * To avoid drift caused by repeated suspend/resumes,
706 * which each can add ~1 second drift error,
707 * try to compensate so the difference in system time
708 * and persistent_clock time stays close to constant.
709 */
710 delta = timespec_sub(xtime, timekeeping_suspend_time);
711 delta_delta = timespec_sub(delta, old_delta);
712 if (abs(delta_delta.tv_sec) >= 2) {
713 /*
714 * if delta_delta is too large, assume time correction
715 * has occured and set old_delta to the current delta.
716 */
717 old_delta = delta;
718 } else {
719 /* Otherwise try to adjust old_system to compensate */
720 timekeeping_suspend_time =
721 timespec_add(timekeeping_suspend_time, delta_delta);
722 }
695 write_sequnlock_irqrestore(&xtime_lock, flags); 723 write_sequnlock_irqrestore(&xtime_lock, flags);
696 724
697 clockevents_notify(CLOCK_EVT_NOTIFY_SUSPEND, NULL); 725 clockevents_notify(CLOCK_EVT_NOTIFY_SUSPEND, NULL);